3-16 &amp; 3-18 - CLIMATIC CHANGE climate is dynamic it...

CLIMATIC CHANGE** climate is dynamic, it doesn't stay the same ** there are daily & monthly & annual averages, SO ** climate changeis a significant change inthese averages over tens or hundreds of thousands of years** climate system; the interaction of all spheres (atmosphere, lithosphere, biosphere, hydrosphere) * when change occurs in one sphere, it affects the other spheres** climates have changed in the past at various times & scales, so will probably continue to change*** Evidence of climate change:Seafloor sediments, Oxygen isotope analysis, Tree rings,Palynology, Geology, Historical Recordssea floor sediments:change in marine life due to changing climate; the relative abundance of warm- and color water species, or morphological variations in a particular species resulting from environmental factors/change.oxygen isotope analysis:the ratio of 18O to 16O in calcareous marine microfauna & from ice cores can indicate glacial vs. inter-glacial periods * this ratio depends on the ocean water T°* 18O doesn’t evaporate out of the seawater as easily as 16O undercolder water conditions, thus more 18O will be left in ocean water & thus more will combine with CaCO3when it recrystallizes to form shell material* SO, when T°s are colder the ratio:-in ice cores is more 16O than 18O than under warmer conditions and in seashells is more 18O than 16O than under warmer conditionstree rings: indicates dry vs. wet periods; relatively short-term* wider rings usually indicate wetter periods & narrower rings drierpalynology (study of fossil pollens):indicate wet vs dry and cool vs warm

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periods by type of plant pollen; certain species may only exist in warm weather, others in cold (tropical plants vs spruce or fir of subpolar region)EX: pollen of spruce species now only found in Canada are found in soil records in Georgia from period of last Ice Age (15,000 ybp)geologic formations:certain formations will only form under certainclimatic conditions, for example coal deposits result from areas of thick vegetation, usually rainforesthuman historical records: anecdotes & observations written down by people about abnormal weather patterns, like a warmer or colder winter than normal* can only go back for relatively for short period of timeChanges in ability of oceans to store CO2, & heatChanges in ocean currents: directions and/or temperatures,Changes in average sea level: change amount of CO2 & heat storedChanges in levels of photosynthesis activity: affect CO2 levelsChanges in storage of carbon in soils: affect CO2 levelsChanges in cloud cover: change temps at the Earth’s surface***Climate change theories:* Non-human Induced Causes:Plate tectonics: land area may "move" into a different climate; could "trigger" a local glacial period, or inter-glacial periodVolcanic activity: increases dust & ash in atmosphere, blocking-out sunshine --> decreasing T°, potentially increasing size of ice massesAstronomical theoryEccentricity: changing the shape of Earth’s orbit;average period of about 95,800 years; varies solar receiptObliquity: changes in

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